It's terrifically hard to diagnose someone you can't hear in person, but I will venture a guess. The chocking sensation is probably due to either a rising larynx or rising tongue. Both of these bad habits develop as compensatory measures for bad breath support. At 55, and after years of what was probably not heatlhy technique, you just can't get away with unsupported singing. Your voice is like a ping pong ball suspended on a column of air. When the airflow isn't consistent the ball drops and either your larynx or your tongue will jump in to catch it (it really doesn't matter which one, the cause is usually the same). DO NOT attempt to fix it by shoving/holding your larynx down or trying to flatten your tongue-that only causes new problems. Solution: Fix the foundation. -Imaging you are wearing a parachute harnass-the area where the straps come up against your lower abdomen (right above your reproductive organs) that part should be firm when you sing-it's the resistance you lean against, it's the foundation that keeps the vocal mechanism functioning. -When you breathe you must realize that the lungs do not just expand in to your chest, they expand 360degrees. This means you must lift your ribcage so that your lungs can expand not only forward, but to the side and to your back (you should feel the ribs streching along your side and you should feel your back expand). -When you sing-let a tiny bit of air escape before the onset. While you sing, it helps to imagine that your body is a hypodermic needle and the diaphragm is the plunger. The plunger moves upward at a consistent speed to expel the air (always with the lower adomen tucked in).